A simple Relay Bypass

[Brett]

Heres my attempt at laying out a vero board for this. Have not verified yet! Looking complicated much?

This uses the Kemet EA2-5SNJ found here at the store.

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View attachment 44958

Don’t forget that any change in relay coil resistance prompts a change in the 150R resistor in the schematic. This relay’s coil resistance is 250 ohms where the circuit is spec’d for a relay coil resistance of 178 ohms.

 

[Chuck D. Bones]

You're looking at the latching coil spec. The EA2 non-latching 5V coil is 178Ω.

 

[JamieJ]

Here's a scoring gauge I just made up:
1 point for each cut.
1 point for each jumper.
1 point for each unused hole. A hole is considered used if it is cut, covered by a component or jumper or used for an external connection.
It's like golf: lower score is better, it can be very Zen and it goes well with alcohol (not too much though).

My score:
12+8+10 = 30
That includes the jumpers on the solder side that join adjacent strips.

Great idea for a thread competition, who can make a Vero layout of a Timmy with the lowest score.

 

[Robert]

Have you considered increasing the value of the current limiting resistor and bypassing it with a capacitor?

It takes more current to latch the relay than it does to hold, you can lower current consumption considerably.

 

[Brett]

You're looking at the latching coil spec. The EA2 non-latching 5V coil is 178Ω.

I screwed up in that I missed that @steviejr92 was planning on using a latching relay (sold here), when this circuit (as designed) requires non-latching.

 

[Chuck D. Bones]

Great idea for a thread competition, who can make a Vero layout of a Timmy with the lowest score.

Maybe something more obscure, there has to be a ton of Timmy Vero layouts on the 'net.

Have you considered increasing the value of the current limiting resistor and bypassing it with a capacitor?

It takes more current to latch the relay than it does to hold, you can lower current consumption considerably.

Definitely doable. Relays don't usually have their guaranteed hold current specified. The Kemet EA2 datasheet specifies a "release voltage," which is not the same as "hold voltage" (or current). We would have to measure a bunch and then add margin. The power saved might be around 1/2 of the nominal 140mW coil power. If you really want low power, then latching relays are the way to go. More expensive and more complicated to drive. TNSTAAFL applies here.

Heres my attempt at laying out a vero board for this. Have not verified yet! Looking complicated much?

This uses the Kemet EA2-5SNJ found here at the store.

Wrong relay. You want the non-latching version.

 

[Feral Feline]

Great idea, another contest …
… for me to miss the deadline for and fail miserably at regardless.

 

[steviejr92]

Maybe something more obscure, there has to be a ton of Timmy Vero layouts on the 'net.


Definitely doable. Relays don't usually have their guaranteed hold current specified. The Kemet EA2 datasheet specifies a "release voltage," which is not the same as "hold voltage" (or current). We would have to measure a bunch and then add margin. The power saved might be around 1/2 of the nominal 140mW coil power. If you really want low power, then latching relays are the way to go. More expensive and more complicated to drive. TNSTAAFL applies here.


Wrong relay. You want the non-latching version.

Wow did not know that! Thank you for that. That just saved me a huge headache!

 

[Chuck D. Bones]

And saved you a few bucks too. From time-to-time, EG puts 5V DPDT relays on sale. Unfortunately, they're out of stock right now.

 

[steviejr92]

Ill be out on the look for them. In the meantime im looking for subs that are closely specced to the one you use.

 

[Chuck D. Bones]

If you get the pinout and coil voltage right, it should work. Like Brett said, we can always change R4 to match the coil resistance.

 

[steviejr92]

Got it! The pinout is what has my attention, the pinout for the relay i was using is opposite than yours. Its part of the reason i have a rats nest on the vero. lol

 

[szukalski]

Worked great on the breadboard with a FTR B4CA!

 

[Silver Blues]

Ok I'm not gonna win any awards based on Chuck's scoring system, but here's another vero layout for you:

Has two standing components, which I hate, but it was the way to get it the most compact.

 

[zgrav]

that is a pretty lean vero layout if the scoring is multiplying rows by columns.

 

[temol]

Slightly off topic - I wanted to buy a few microcontrollers for the bypass system. Last time I paid about $1 each. Now they are $2 to $4. Looks like the 555 is a nice price alternative.

 

[szukalski]

Got my PCBs in today. Ignoring the silly location of the SPST pads, it works pretty well and is nice and compact.
Compact enough that I will look at a different layout where the SPST is attached to the PCB (yet still 1590B friendly).

 

[Brett]

Got my PCBs in today. Ignoring the silly location of the SPST pads, it works pretty well and is nice and compact.
Compact enough that I will look at a different layout where the SPST is attached to the PCB (yet still 1590B friendly).

View attachment 45490

Nice looking board @szukalski! I'm looking forward to see your switch-mounted option for 1590b!

I haven't sent these off for fabrication yet, but they're designed for foot switch mounting in a 125b. *The cutout next to the switch is to accommodate the LED bezel housing.
9V only board:

9-30VDC option:


Edit: I forgot to show a mockup of the side view of this switch-mounted board. The PCB is not to scale but hopefully this gives the idea.


I've been enjoying seeing all the PCBs and faceplates you've designed, they look awesome!

 

[steviejr92]

Wow im super impressed by both @szukalski and @Brett boards! Awesome work guys!

 

[Chuck D. Bones]

Note the judicious use of the White Washer.